This invention relates to apparatus for mechanically chopping, shearing or shredding solid materials such as scrap automobile and truck tires; scrap insulated electrical conductors; beverage cans; and other solid waste materials required to be reduced to substantially uniform smaller particulate sizes for efficient permanent disposal, commercial recycling, or other utilization. Typically, systems for such purposes include conveyor means for carrying materials to be processed from ground level to the in-feed of a chopper or shredding machine (which for convenience will hereinafter be referred to as the shredder); a screening (or "classifying") device for receiving the produce from the shredder and passing to discharge product fragments of prescribed sizes; and elevator means for returning oversized products to the shredder mechanism. Machines for similar purposes are disclosed for example in U.S. Pat. Nos. 3,578,252; 3,656,697; 3,727,850; 3,841,570; 3,931,935; 4,134,556; 4,156,508; 4,216,916; 4,363,45O; 4,684,070 and 4,684,071.
The shredder component of such systems typically comprises a multiplicity of spaced apart discs carried by parallel mounted counter-rotating drive shafts in such manner that the discs of one shaft interdigitally project at their perimetral regions in between the discs carried by the other shaft. The discs mount around their perimetral rims successions of canted cutting blades as shown for example at 26 in U.S. Pat. No. 4,684,071 and at 174 in U.S. Pat. No. 4,374,573. As best shown at FIGS. 10 and 11 of U.S. Pat. No. 4,374,573, replaceable abrasion resistant wearing plates 172 are mounted on opposite sides of the discs under the "cutter segments" 174. Whereas the provision of rotating disc protecting replaceable wearing plates for such purposes has proven to be of important economic advantage, the means shown therein for exchanging new plates for worn plates on the cutter discs has proven to require difficult and time-consuming and therefore unduly expensive maintenance work; and it is the object of the present invention to provide an important improvement in the means for installing such plates to the cutter discs, and for facilitating the replacement of plates for worn plates.